Guardrail systems are one example of traffic barriers placed along roadsides to screen errant vehicles from hazards behind the barrier. Guardrail systems are frequently constructed using steel W-beams mounted on wood or steel posts. Thrie beams may also be used to form all or portions of a guardrail system. Both W-beams and thrie beams function primarily in tension to redirect an impacting vehicle. Therefore, the ends of a typical guardrail system are securely anchored to allow the associated beams to develop desired tensile forces. In addition, since the ends of a guardrail system represent a discontinuity in the barrier, the end facing oncoming traffic is subject to being struck “head-on” by vehicles with small departure angles from an adjacent roadway. The end facing oncoming traffic may also be struck by the side of a vehicle. The end of the guardrail may spear the vehicle during a head-on impact or a side impact. One widely used end terminal design “buries” a W-beam at the end of the guardrail facing oncoming traffic to eliminate spearing.
Development of guardrail end terminals and crash cushion designs is complicated by the need to minimize resistance to small car impacts while still providing necessary energy absorbing capability for full-size car impacts. Such impacts may occur with the end or downstream from the end of a guardrail system or other traffic barrier. U.S. Pat. Nos. 4,655,434 and 5,957,435 to Maurice E. Bronstad, disclose guardrail end terminals having beams with spaced openings to absorb kinetic energy of an impacting vehicle. U.S. Pat. No. 6,129,342 to Maurice Bronstad discloses a guardrail end terminal modified to accommodate impact from the side of a vehicle.